1. Field of the Invention
The present invention relates to a printed substrate wiring device for connection to electrode-including optical elements such as photodiodes and semi-conductor lasers provided in chip form, and an optical head device using the same printed substrate.
2. Description of the Prior Art
In video disk and digital audio disk media, an information signal is recorded by forming a spiral track of pits corresponding to the information signal through the irradiation of the record surface of the disk with a fine spot of light. Further, in the case where the information signal thus recorded is to be reproduced, the original information signal is reproduced in accordance with the changes in the light reflected by or transmitted through the media upon irradiation of the track with a light source.
Various types of optical head devices for performing the aforementioned recording and reproducing functions have been developed. For example, these optical head devices include light-emitting elements, such as semiconductor lasers and the like; objective lenses for converging light emitted from the light-emitting elements onto the recording surface of the disk in the form of a spot; and light receiving elements, such as photodiodes or the like, for receiving light reflected from the recorded surface of the disk for generating a signal corresponding to the conditions of their light reception.
Referring to FIG. 6, there is shown a member used in a conventional optical head device, in which a semiconductor laser 51 in raw chip form is housed in an airtight package 55 constituted by a cylindrical portion 52, a glass plate 53 and a cover 54 and is connected to terminals 56 by wiring (not shown). The member together with other optical members, is attached to a body 57 as shown in FIG. 7. Referring to FIG. 8, there is shown another member used in the conventional optical head device, in which photodiodes 59 and 60 provided in chip form are sealed within a package 61 formed by a molded resin and are connected to terminals 62 by wiring (not shown). This member is also attached to the body 57 as shown in FIG. 7. The relative positions of the semiconductor laser and photodiodes are adjusted with high accuracy so that the laser light reflected from the recorded surface of the disk 64 is precisely incident upon the photodiodes 59 and 60.
In order to assemble the semiconductor laser 51 and photodiodes 59 and 60 while maintaining this predetermined relation in the relative positions thereof, conventionally, these elements are housed in their respective exclusive packages 55 and 61 and then the packages are attached to the body 57.
The semiconductor laser 51 and photodiodes 59 and 60 in themselves are very small parts, but the packages 55 and 61 surrounding them are relatively large. Accordingly, the body 57 supporting the packages also becomes a large member. This is a problem to be solved in the miniaturization of the optical head device.
Recently it has been considered that the semiconductor laser and photodiodes may be formed in the raw chip state and assembled without use of the aforementioned packages. However, it is difficult to assemble the semiconductor laser and photodiodes while positioning them with high accuracy, because they are very small in size as described above.
Where the relative positions of the semiconductor laser and diode are to be adjusted, this is done by observing the light reception condition of the photodiode due to the light emitted from the semiconductor laser. Toward this end, electrical power is supplied to the wiring attached to the two parts, with the wiring arranged in a manner such that the relative positions of the two parts can be changed on the basis of the results of the measurement. However, it is particularly difficult to form the complex wiring so that the positions of the small-scale semiconductor laser and diodes can be suitably changed. Accordingly, the development of wiring to make this task easy has been desired.